Broken Access Control occurs when an authenticated user exceeds their intended privileges, such as a regular user accessing an admin panel. To mitigate OWASP A1 vulnerabilities, F5 TMOS requires three key protections:
- Secure F5 TMOS by configuring passwords and Role-Based Access Control (RBAC) for TMOS users.
2. Implement F5 ASM Module Mitigations.
3. Apply F5 APM Module Protections.
Below are the first four F5 ASM configurations to defend against OWASP A1:
1️⃣ Attack Signatures: Predictable Resource Locations & Path Traversal
– Predictable Resource Locations Signatures block access to sensitive files (e.g., .NET’s web.config).
– Path Traversal Signatures prevent attackers from escaping the web app directory to access OS files.
2️⃣ URLs: Allowed & Disallowed URLs
- Use Positive Security Model (whitelist allowed URLs) or Negative Security Model (blacklist disallowed URLs like `/admin` for external users).
3️⃣ URL Flows
- Enforce logical navigation (e.g., users must visit `/login` before accessing
/profile).
4️⃣ Login Pages
- Prevent forceful browsing by requiring authentication before accessing protected resources.
You Should Know:
F5 ASM CLI Commands for Mitigation
Enable Attack Signatures tmsh modify security firewall policy <policy_name> attack-signatures enabled Block Path Traversal tmsh create security firewall policy <policy_name> rule <rule_name> action block path-traversal Configure URL Filtering tmsh create security firewall policy <policy_name> rule <rule_name> action reject url "/admin" Enforce URL Flow tmsh modify security firewall policy <policy_name> rule <rule_name> condition "http-referer contains '/login'"
Linux Commands for Access Control Testing
Check file permissions (Linux) ls -la /var/www/html Test Path Traversal (CURL) curl -v http://example.com/../../etc/passwd Simulate Broken Access Control (HTTP Requests) curl -H "Cookie: admin=true" http://example.com/admin-panel
Windows Command for RBAC Verification
Check User Privileges (PowerShell) Get-LocalUser | Select Name, Enabled, PrincipalSource Audit File Access icacls C:\inetpub\wwwroot\web.config
What Undercode Say:
F5 ASM’s layered security approach effectively mitigates Broken Access Control by combining signature-based detection, URL filtering, and flow enforcement. However, administrators must regularly update attack signatures and test configurations to avoid false negatives.
For Linux admins, hardening file permissions (chmod 640) and implementing SELinux policies can further restrict unauthorized access. Windows admins should enforce Group Policy Objects (GPOs) to limit user privileges.
Automate F5 ASM rule updates via:
tmsh load sys config merge from-terminal
Expected Output:
- Blocked `/admin` access from external IPs.
- Detected and logged path traversal attempts.
- Enforced login redirection for unauthenticated users.
Prediction:
As APIs grow, Broken Access Control will shift towards misconfigured JWT tokens and excessive API permissions. F5 ASM’s machine learning features may soon auto-tune policies based on traffic patterns.
Relevant URL: OWASP Broken Access Control
References:
Reported By: Grahammattingley Owasp – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
